Control surface assemblies with torque tube base

ABSTRACT

Control surface assemblies having a torque tube base are disclosed. In one embodiment, a method includes providing a control surface assembly including: providing a control surface portion having a pair of longitudinal surfaces, providing a hollow base portion coupled to the control surface portion, the base portion including an elongated curved wall, and an elongated base plate disposed crosswise to the pair of the longitudinal surfaces having at least one aperture disposed therein, and a plurality of attachment flanges extending laterally outwardly beyond the longitudinal surfaces; coupling the attachment flanges to a supporting structure of a vehicle such that the control surface portion projects outwardly from the supporting structure; moving the vehicle through a medium; and moving at least a portion of the control surface assembly to generate a force on the vehicle.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional application of co-pending,commonly-owned U.S. patent application Ser. No. 11/043,918 entitled“Control Surface Assemblies with Torque Tube Base” filed on Jan. 21,2005, which application is incorporated herein by reference.

GOVERNMENT LICENSE RIGHTS

This invention was made with Government support under U.S. Governmentcontract F33615-98-9-2880 awarded by United States Air Force. TheGovernment has certain rights in this invention.

FIELD OF THE INVENTION

This invention relates to structures for flight vehicles, and morespecifically, to control surface assemblies having a torque tube base.

BACKGROUND

Many types of aerospace vehicles include one or more control surfacesthat project outwardly from a main body of the vehicle to enhance or toenable proper control of the vehicle. Typically, such control surfacesare designed to meet anticipated load requirements associated withcontrol of the vehicle. Among the considerations involved in the designof such control surfaces is the stiffness of the control surface toavoid flutter. More specifically, to avoid flutter of a control surface(e.g. a control fin) it is typically necessary to increase thefundamental mode shape frequencies.

For example, FIGS. 1 and 2 show simplified cross-sectional views ofcontrol surface assemblies in accordance with the prior art. In FIG. 1,a control surface assembly 100 includes an outwardly-projecting controlsurface portion 102 coupled to a flat flange portion 104 that attachesto an aerospace vehicle 106 (e.g. a missile, an aircraft, etc.).Typically, the control surface assembly 100 is efficient in bendingstiffness, but is relatively less efficient in providing torsionalstiffness. In FIG. 2, a control surface assembly 200 includes anon-uniformly tapered outwardly-projecting control surface portion 202coupled to a base portion 204 having a solid support member 205. Thebase portion 204 is coupled to a fuselage (or body) 206. The controlsurface assembly 200 is typically less efficient in bending stiffnessthan the control surface assembly 100 having the flat flange portion 104however, the control surface assembly 200 may exhibit improved torsionalstiffness over the control surface assembly 100 due to the stiffness ofthe solid support member 205.

Although desirable results have been achieved using the prior artcontrol surface assemblies shown in FIGS. 1 and 2, there may be room forimprovement. For example, for at least some applications, the prior artassemblies may exhibit undesirable weight and heat transfercharacteristics. Therefore, improved control surface assemblies that atleast partially mitigate these undesirable characteristics would haveutility.

SUMMARY OF THE INVENTION

The present invention is directed to control surface assemblies having atorque tube base. Embodiments of the present invention mayadvantageously provide a desired degree of bending and torsionalstiffness, with improved weight and heat transfer characteristics incomparison with the prior art.

In one embodiment, a method includes providing a control surfaceassembly including: providing a control surface portion having a pair oflongitudinal surfaces, providing a hollow base portion coupled to thecontrol surface portion, the base portion including an elongated curvedwall, and an elongated base plate disposed crosswise to the pair of thelongitudinal surfaces having at least one aperture disposed therein, anda plurality of attachment flanges extending laterally outwardly beyondthe longitudinal surfaces; coupling the attachment flanges to asupporting structure of a vehicle such that the control surface portionprojects outwardly from the supporting structure; moving the vehiclethrough a medium; and moving at least a portion of the control surfaceassembly to generate a force on the vehicle.

The features, functions, and advantages that have been discussed can beachieved independently in various embodiments of the present inventionor may be combined in yet other embodiments further details of which canbe seen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are described in detail below withreference to the following drawings.

FIG. 1 is an end cross-sectional schematic view of a control surfaceassembly in accordance with the prior art;

FIG. 2 is an end cross-sectional schematic view of another controlsurface assembly in accordance with the prior art;

FIG. 3 is an end cross-sectional view of a control surface assembly inaccordance with an embodiment of the present invention;

FIG. 4 is an isometric view of the control surface assembly of FIG. 3coupled to a vehicle in accordance with another embodiment of theinvention;

FIG. 5 is an isometric view of the control surface assembly of FIG. 3 inan inverted position; and

FIG. 6 is an isometric view of an aircraft having a plurality ofmissiles in accordance with further embodiments of the presentinvention.

DETAILED DESCRIPTION

The present invention relates to control surface assemblies having atorque tube base. Many specific details of certain embodiments of theinvention are set forth in the following description and in FIGS. 1-6 toprovide a thorough understanding of such embodiments. One skilled in theart, however, will understand that the present invention may haveadditional embodiments, or that the present invention may be practicedwithout several of the details described in the following description.

FIG. 3 is an end cross-sectional view of a control surface assembly 300in accordance with an embodiment of the present invention. FIG. 4 is anisometric view of the control surface assembly 100 of FIG. 3 coupled toa vehicle fuselage 306. In this embodiment, the control surface assembly300 includes an outwardly-projecting control surface portion 302 coupledto a hollow, shell-like base portion 304 having a thickness t. Theoutwardly-projecting control surface portion 302 may be tapered(uniformly or non-uniformly) as shown in FIG. 3, or alternately, may beof uniform thickness or width, or any other suitable combinationthereof.

In one embodiment, the base portion 304 includes a rounded (or arcuate)member 314 (FIG. 3) that forms a substantially hollow (or tubular)section. In some embodiments, the rounded member 314 may have asemi-circular (or partially semi-circular) cross-sectional shape, andmay be completely enclosed, as shown in FIG. 3, or alternately, it maybe only partially closed. As best shown in FIG. 4, the rounded member314 comprises an elongated main portion 308 having a pair of tapered endportions 310. The base portion 304 further includes a plurality ofattachment flanges 312 for coupling the base portion 304 to the aircraft306. The control surface portion 302 is coupled to the rounded member314 and projects outwardly from the fuselage 306 by a height H. Asfurther shown in FIG. 3, the base portion 304 has a width W.

FIG. 5 is an isometric view of the control surface assembly 300 of FIG.3 in an inverted position. As shown in FIG. 5, the base portion 304 mayfurther include a plurality of span members 318 that span betweenopposing lateral sides of the rounded member 314, and which are formedbetween a plurality of gaps 320 having a gap width G. In thisembodiment, the base portion 304 includes multiple attachment flanges312 suitable for fixed aero-surface configurations such as strakes orfences. In alternate embodiments, the base portion 304 may include onlya single attachment point, such as for rotating control surfaceconfigurations.

In operation, the control surface assembly 300 provides increasedfundamental mode shape frequencies to avoid flutter. Because the baseportion 304 of the control surface assembly 300 is a hollow, shell-likestructure, the base portion 304 advantageously provides suitabletorsional stiffness characteristics by increasing the frequency ofmultiple mode shapes (e.g. plate bending and plate torsion) while alsoproviding improved weight characteristics. In one particular aspect, thesubstantially-hollow main portion 308 may provide a highly efficientstructure for meeting the desired torsional stiffness characteristics.In addition, the hollow base portion 304 may provide suitable bendingstiffness.

In some embodiments, the base portion 304 of the control surfaceassembly 300 may provide a substantial weight savings over comparableprior art assemblies. In one particular embodiment, for example, a 30%or higher weight savings may be achieved. Substantial weight savings maybe achievable for both metal and composite control surface assemblies.Furthermore, for high temperature applications, the base portion torquetube feature between the attach points, allows a reduced amount ofcontact area required for attachment. This may advantageously reduce orminimize the amount of heat transfer from the control surface portion302 into the fuselage 306 compared with prior art apparatus.

For applications that require enhanced stiffness of control surfaceassemblies, prior art methods of adding bending stiffness includedsimply thickening the outwardly-projecting portion and the base portion.It has been determined, however, that there is a point of diminishingreturns for blade thickening because the added mass offsets theincreased blade/plate bending stiffness. Furthermore, in one particularembodiment, the hollowed base portion 304 of the control surfaceassembly 300 provides a lowest natural frequency of a plate bending modeof approximately 120 Hz, and approximately 150 Hz for a first platetorsion mode, as compared with a lowest natural frequency of 60 Hz forthe plate bending mode and approximately 90 Hz for the first platetorsional mode for the flat flange 104 of the assembly 100 shown inFIG. 1. These data demonstrate that embodiments of the invention maysimultaneously increase the frequency of multiple mode shapes.Furthermore, the control surface assembly 300 may be substantiallylighter than the flat flange assembly 100 of the prior art.

It will be appreciated that control surface assemblies in accordancewith the present invention may be used on a variety of vehicles andsystems, including but not limited to any suitable type of aerospacevehicles. For example, FIG. 6 is an isometric view of an aircraft 1000having a plurality of missiles 150 in accordance with furtherembodiments of the present invention. The aircraft 1000 includes avariety of known components, including a fuselage 1002, lift generatingsurfaces 1004 (e.g. wings), a propulsion system 1006, a control system1010, and a host of other systems and subsystems that enable properoperation of the aircraft 1000. The aircraft 1000 also includes a tailassembly 1020 having a pair of vertical fins 1022 and a pair ofhorizontal fins 1024 (only one visible). The fins 1022, 1024 maysuitably be control surface assemblies in accordance with embodiments ofthe present invention.

In addition, each of the missiles 1050 may include a variety of knowncomponents, including a fuselage 1052, a plurality of control surfaces(or fins or strakes) 1054 coupled to the fuselage 1052, a propulsionsystem 1056, a control system 1062, and other systems and subsystemsthat enable proper operation of the missile 1050. Each of the controlsurfaces 1060 may suitably be control surface assemblies in accordancewith embodiments of the present invention.

In one embodiment, the aircraft 1000 may be a fighter aircraft, such as,for example, an F/A-18E Super Hornet manufactured by The Boeing Companyof Chicago, Ill. However, it will be appreciated that embodiments ofcontrol surface assemblies in accordance with the present invention maybe included in any other suitable aircraft. For example, in alternateembodiments, the aircraft may be a fighter aircraft, a rotary aircraft,a bomber aircraft, or any other suitable type of manned or unmannedaircraft, including those described, for example, in The IllustratedEncyclopedia of Military Aircraft by Enzo Angelucci, published by BookSales Publishers, September 2001, and in Jane's All the World's Aircraftpublished by Jane's Information Group of Coulsdon, Surrey, UnitedKingdom, which texts are incorporated herein by reference. Similarly,the missiles 1050 may be any suitable type of missiles that include amovable or non-movable control surface assemblies, including but notlimited to Harpoons, HARMs, Sparrows, AMRAAMs, or any other suitablemissiles, including those described in the above-referenced texts.

While preferred and alternate embodiments of the invention have beenillustrated and described, as noted above, many changes can be madewithout departing from the spirit and scope of the invention.Accordingly, the scope of the invention is not limited by the disclosureof these preferred and alternate embodiments. Instead, the inventionshould be determined entirely by reference to the claims that follow.

1. A method of controlling a vehicle, comprising: providing a control surface assembly coupled to the vehicle, wherein providing the assembly includes: providing a control surface portion having a pair of longitudinal surfaces; providing a hollow base portion coupled to a first end portion of the control surface portion, the base portion including an elongated curved wall, and an elongated base plate disposed crosswise to the pair of the longitudinal surfaces having at least one aperture disposed therein, and a plurality of attachment flanges extending laterally outwardly beyond the longitudinal surfaces; and coupling the attachment flanges of the elongated base plate of the control surface assembly to a supporting structure of the vehicle such that the control surface portion projects outwardly from the supporting structure; moving the vehicle through a medium; and moving at least a portion of the control surface assembly to generate a force on the supporting structure of the vehicle.
 2. The method of claim 1, wherein providing a hollow base portion including an elongated curved wall and an elongated base plate includes providing an elongated curved wall and an elongated base plate that cooperatively define a hollow region, and providing a control surface portion includes providing a control surface portion that projects from the elongated curved wall.
 3. The method of claim 2, wherein providing an elongated curved wall and an elongated base plate that cooperatively define a hollow region includes defining a hollow region that has a semi-circular cross-sectional shape.
 4. The method of claim 1, wherein providing a control surface assembly includes providing a pair of tapered end portions formed at opposing ends of the base portion.
 5. The method of claim 1, wherein providing a hollow base portion including an elongated base plate includes providing the elongated base plate with a plurality of gaps.
 6. The method of claim 1, wherein providing a hollow base portion includes providing the base portion having a plurality of apertures.
 7. The method of claim 6, wherein providing the base portion with at least one attachment point configured to be coupled to the support structure includes providing the base portion having a plurality of elongated apertures, the base plate further including at least one span member extending laterally between the plurality of apertures.
 8. A method, comprising: providing an assembly comprising a control surface portion coupled to a base portion, the base portion being coupled to a support structure such that the control surface portion projects outwardly from the supporting structure, the base portion including: an elongated curved wall; and an elongated base plate coupled to the elongated curved wall and having at least one aperture disposed therein, and a plurality of laterally outwardly extending attachment flanges, the attachment flanges being coupled to the support structure; and actuating at least a portion of the control surface portion to generate an aerodynamic control force.
 9. The method of claim 8, wherein providing an assembly includes providing an assembly wherein the elongated curved wall and the elongated base plate cooperatively define a hollow region, and the control surface portion projects from the elongated curved wall.
 10. The method of claim 9, wherein providing an assembly includes providing an assembly wherein the hollow region has a semi-circular cross-sectional shape.
 11. The method of claim 8, wherein providing an assembly includes providing an assembly wherein the base portion includes a pair of tapered end portions formed at opposing ends of the base portion.
 12. The method of claim 8, wherein providing an assembly includes providing an assembly wherein the at least one aperture disposed in the base plate includes a plurality of apertures.
 13. The method of claim 8, wherein providing an assembly includes providing an assembly wherein the at least one aperture disposed in the elongated base plate includes a plurality of elongated apertures, the base plate further including at least one span member extending laterally between the plurality of apertures.
 14. The method of claim 8, further comprising moving the support structure through a medium.
 15. The method of claim 14, wherein moving the support structure through a medium includes propelling an aircraft through the medium. 